Problem: Gabriela ate 5 slices of pizza. William ate 4 slices. If Gabriela ate $\dfrac{5}{10}$ of the pizza, what fraction of the pizza was eaten?
If 5 slices represent $\dfrac{5}{10}$ of the pizza, there must have been a total of 10 slices. $\text{fraction of pizza eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${9}$ out of $10$ slices. They ate $\dfrac{9}{10}$ of the pizza.